Underwater photos can often captivate viewers, offering a glimpse into the world below the ocean's surface. Reddit user "kwajajosh" shared these amazing undersea photos on the occasion of his 100th Scuba dive on July 30. From lively fish to delicate coral, these undersea pictures provide an up-close look at a precious ecosystem that is in need of protection.

According to the diver, all of these photos were taken in the Marshall Islands. The islands were a garrison of the Japanese navy during World War II, and were conquered by American forces during the Gilbert and Marshall Islands campaign. This may account for the military wreckage that can be seen in some photos.

Scroll Down For Photos

From 1946 to 1958, the islands were the site of the Pacific Proving Grounds, where 67 atomic weapons were tested by the U.S. government. The United States would later pay more than $759 million to residents of the islands in compensation for exposing them to radiation from nuclear tests.

In 2011, the Marshallese government established a 772,000-square mile shark sanctuary in the islands. It is the largest shark sanctuary in the world. While shark fishing is outlawed in the sanctuary, and all bycatch must be released, some have questioned the ability of the local government to enforce the regulations.

While several examples of bright corals can be seen in these photos, some Reddit users pointed out that the overall scene is not as vibrant as one might expect. Although this could be the result of the subject's distance from the flash (as color does not travel very far beyond certain depths), it does call to mind the threat of ocean acidification, which threatens reefs around the world.

Ocean acidity, which occurs as the seas absorb excess carbon dioxide from the atmosphere, has risen by 30 percent in the past 250 years, according to the Natural Resources Defense Council.